In recent years, hybrid vehicles are increasingly gaining attention as ecologically friendly vehicles. Hybrid vehicles have in addition to a conventional internal combustion engine as a further motive power source a battery or a similar electric power storage device and an electric motor receiving electric power from the electric power storage device to use it to generate force driving the vehicle.
Japanese Patent Laying-Open No. 2005-137135 discloses a control device for a hybrid vehicle employing one or both of an engine and a motor as a braking and driving motive power source and communicating electric power between the motor and a battery.
The control device includes: a vehicular speed detection means detecting vehicular speed; braking and driving motive power control value setting means setting a braking and driving motive power control value for a vehicle; SOC detection means detecting a battery's state of charge (SOC); and a navigation device setting a traveling route for the vehicle and detecting the traveling route's road environment information.
The control device further includes: first efficiency index calculation means calculating an efficiency index value based on the traveling route's road environment information and the SOC and representing fuel utilization efficiency; second efficiency index calculation means calculating an efficiency index value based on the SOC to have larger values for larger SOCs; final efficiency index calculation means that selects the first efficiency index value obtained by the first efficiency index calculation means if the road environment information of the traveling route of the vehicle can be detected, otherwise selects the second efficiency index value obtained by the second efficiency index calculation means, and that in switching the efficiency index value performs a process to continuously change the efficiency index value from a value that the efficiency index value has before the efficiency index value is switched to match the efficiency index value to a value that should be attained after the efficiency index value is switched to obtain a final efficiency index value; and operation point determination means determining a point of operation of the engine and motor, as based on the detected vehicular speed value, the braking and driving motive power control value and the final efficiency index value, to allow the battery to be charged with smaller amounts for larger final efficiency index values.
The control device has one feature in that once a vehicle has reached a geographical point having within a predetermined distance a distance Xr to an end of a traveling route set by navigation, the final efficiency index calculation means calculates an efficiency index value to be farther away from the first efficiency index value and closer to the second efficiency index value as distance Xr decreases to be smaller.
A known hybrid vehicle has an externally charging function allowing a power supply external to the vehicle to be used to charge an electric power storage device. The hybrid vehicle having the externally charging function can be less dependent on an internal combustion engine. This can eliminate the necessity of the vehicle frequently going to a gas station to be refueled, and can also contribute to further environmental protection.
The technique disclosed in Japanese Patent Laying-Open No. 2005-137135 may be applied to a hybrid vehicle having the externally charging function. In other words, the vehicle is charged at an end of a traveling route. This would allow charging the vehicle to be started in a condition allowing large electric power to be charged.
However, the vehicle that has arrived home may immediately thereafter again leave home. In that case, if the vehicle is charged for example at home, the vehicle will not be externally charged, or will be charged for a short period of time and thus insufficiently charged, and leave.